Technical Field
The present invention relates to an air supply damper employed in a smoke control system provided in a high-rise building, and more particular, to an air supply damper having a function for separately supplying leakage air flow and supplementary air flow, which is connected to a utility-pipe conduit which separately supplies leakage air flow and supplementary air flow, to separately adjust the supply of leakage air flow and supplementary air flow for preventing in advance, differential pressure between an accommodation and a lobby (smoke control zone) from becoming lower or higher than a standard value, and to provide occupants with safety evacuation conditions in case of a fire in the building, a method for controlling the same and a smoke control system utilizing the same.
Background Art
In general, as buildings become larger, higher and more complex due to integration and sophistication of the metropolis, buildings which are vulnerable to fire have increased, thus an effective fire prevention measure ensuring safety of life is urgently required.
In particular, the importance of a smoke control system for controlling smoke, which causes inconvenience during evacuation and fire extinguishing activities and poses a significant threat to the safety of life when a fire occurs in a building, has been emphasized.
In Korea, in order to prevent smoke from penetrating into an evacuation stairwell and to secure safety evacuation routes, a design guide for a smoke control system of a special evacuation stairwell and lobby according to NFSC (National Fire Safety Codes 501A) has been proposed.
The above design guide requires that a differential pressure of 40 Pa (in the case where a sprinkler is provided, 12.5 Pa) should be maintained between smoke control zones to prevent smoke from penetrating into a smoke control zone and an accommodation, a force required for opening a door of the smoke control zone should be 110 N or less, and air egress velocity of 0.5 m/s to 0.7 m/s or more should be obtained in a case where the door of the smoke control zone is temporarily opened for evacuation.
A method which has been widely utilized for achieving the above purpose is a pressurized smoke control system which employs a smoke control blower and a vertical flow passage to supply external air into a lobby located between an accommodation and a staircase, thereby controlling smoke in the lobby.
The above conventional pressurized smoke control system 1 is illustrated in FIGS. 1A and 1B.
As shown in FIGS. 1A and 1B, that is, the above conventional pressurized smoke control system adopts the manner in which external air is supplied through an air supply damper 32 provided in a lobby 40 among an accommodation 30, a corridor of the building, and a staircase 50 by means of an air supply blower 10 for controlling smoke and one air supplying passage 20 passing a utility-pipe conduit 22 to increase pressure in the lobby 40.
The lobby 40 is set as a smoke control zone, and in order to prevent smoke from being penetrated from the accommodation 30 in which a fire occurs to the lobby 40, the above conventional pressurized smoke control system 1 maintains a differential pressure, which is a larger than a standard value, between the lobby 40 and the accommodation 30. And, in order to keep a force required for opening a door 42 below a certain standard to make it easier for occupants to open the door 42, that is, in order to prevent an overpressure from being formed in the lobby 40, the conventional pressurized smoke control system adjusts the differential pressure between the lobby 40 and the accommodation 30 to a range (standard value) between an upper limit and a lower limit.
At this time, in order to maintain the differential pressure according to a standard value, when the differential pressure is formed between the lobby 40 and the accommodation 30, the amount of air supplied into the lobby should be as much as the amount of air leaked from the lobby 40 through a gap between a wall and the door 42 of the lobby 40. The amount of air to be supplied into the lobby for this condition is referred to as “leakage air flow”.
In the meantime, in the case where the door 42 of the lobby 40 is temporarily opened, in order to maintain the air egress velocity required for preventing smoke from being introduced from the accommodation 30 to the lobby 40, external air should be supplied to the lobby. The amount of air supplied into the lobby for this condition is referred to as “supplementary air flow”.
In the design of the conventional pressurized smoke control system 1, in view of the above, leakage air flow and supplementary air flow are calculated, and the amount of air supply of the blower for controlling smoke is then calculated as the sum of the supplementary air flow and the leakage air flow, and is supplied into the lobby.
In the conventional pressurized smoke control system 1, in addition, in the case where the amount of air supply calculated by adding the supplementary air flow and the leakage air flow is supplied to the lobby 40 of each floor from the smoke control blower 10 through a vertical air flow passage 22, it is necessary to adjust the amount of air supplied into the lobby 40 of each floor.
In other words, as illustrated, if the door 42 of the lobby 40 is closed, a differential pressure which is larger than a certain standard should be maintained to prevent smoke from penetrating through a gap between a wall and the door. In order to allow an occupant to open the door without any difficulty during evacuation, overpressure should be simultaneously prevented in order to lower an opening force required for opening the door to less than a certain standard, that is, for preventing overpressure from being generated in the lobby 40.
For the above purpose, the amount of air (air volume) supplied into the lobby of each floor should be adjusted so as to adjust the differential pressure between the lobby and the accommodation within a range between the upper limit and the lower limit.
In addition, when the door of the lobby is opened, the amount of the air supplied into the lobby to generate air egress velocity should be more than a standard value.
In order to satisfy design conditions of the pressure the air egress velocity in the lobby, the automatic differential pressure and overpressure control-type air supply damper 32 has been employed in a majority of buildings.
As shown in FIG. 2A, the automatic differential pressure and overpressure control-type air supply damper 32 is provided between a wall of the lobby 40 and the air supplying passage 20. A damper blade 32ais normally shut to not allow air current to be flowed between the lobby 40 and the air supplying passage 20, and if a fire occurs, as shown in FIG. 2B, the damper blade 32ais rotated by a driving motor 32b to supply air to the air supplying passage 20 in the lobby 10.
At this time, a pressure sensor and the like senses a differential pressure between the lobby 40 and the accommodation 30 to adjust an opening degree of the damper blade 32 for adjusting amount of air supplied to the lobby, consequently, a maintenance of the differential pressure between lobby 40 and the accommodation 30, a prevention of overpressure and a formation of the air egress velocity are automatically performed.
Accordingly, once the fire occurs, the conventional automatic differential pressure and overpressure control-type air supply damper 32 is operated and the damper blade 32a is opened to supply the air required for controlling the smoke into the lobby.
And, the opening degree of the damper blade 32a is increased until the differential pressure between the lobby 40 and the accommodation 30 is reached to the designed differential pressure to increase the amount of air supplied into the lobby.
While the differential pressure is increased according to the amount of air supplied into the lobby, once the differential pressure becomes larger than the designed the differential pressure, the opening degree of the damper blade 32a is decreased in the reverse direction to reduce the supplied amount of air and reduce the differential pressure between the lobby 40 and the accommodation 30.
However, if the differential pressure is smaller than the designed differential pressure, the opening degree of the damper blade 32a is again increased to increase amount of air. In other words, the differential pressure formed between the lobby 40 and the accommodation 30 is compared with the designed differential pressure and amount of supplied air is adjusted according to the result of comparison.
Meanwhile, once the door 42a of the lobby 40 is opened and the differential pressure becomes nearly 0 (zero), the damper is completely opened to 100% and amount of supplied air is maximized to form the air egress velocity toward the door is formed.
As illustrated above, the conventional automatic differential pressure and overpressure control-type air supply damper 32 senses the differential pressure formed between the lobby 40 and the accommodation 30 through the pressure sensor, adjusts the opening degree of the damper blade to maintain the differential pressure formed between the lobby 40 and the accommodation 30 to the designed differential pressure and forms simultaneously the air egress velocity at the time of opening the door.
However, after reviewing a result of the in-site performance evaluation of the pressurized smoke control system 1 installed and operated in the real building, it is found that the pressurized smoke control systems 1 in the considerable number of buildings do not show the designed performances. In other words, there are frequent occasions when the differential pressure formed between the accommodation 30 and the lobby 40 which is a smoke control zone is formed as an overpressure exceeding the standard value or as a low pressure smaller than the standard value.
In particular, it can be seen that when the door 42 of the lobby 40 is opened according to an evacuation of occupants, the differential pressure in a floor besides the floor in which the opened door, which is maintained as the proper value prior to opening the door is significantly lowered.
The fundamental factors causing above conditions can be found from the design concept in which amount of air to be supplied is calculated as the sum of leakage air flow and supplementary air flow and this amount of air to be supplied is supplied to one vertical air supply passage 20 and an operation of the conventional automatic differential pressure and overpressure control-type air supply damper 32 which controls simultaneously amount of the leakage air flow and amount the supplementary air flow to be supplied.
In addition to the normal leakage air flow for forming the proper differential pressure for controlling smoke, the supplemental air flow for satisfying the air egress velocity is additionally supplied so that in the case where the doors of all the floors are closed, the excessive amount of air is supplied.
In addition, once the door 42 of the lobby 40 is opened, since some of the leakage air flow together with the supplementary air flow are exhausted from the floor in which the door is opened, amount of air which is smaller than the normal leakage air flow is supplied to another floor so that the differential pressure which is smaller than the standard value is formed between the accommodation 30 and the lobby 40.
In view of the above, like the design concept of the pressurized smoke control system 1, if the smoke control system 1 designed on the basis of the conventional automatic differential pressure and overpressure control-type air supply damper 32 in which leakage air flow and supplementary air flow are simultaneously supplied through one air supply passage 20 and leakage air flow and supplementary air flow are supplied to the same flow passage and controlled is installed and operated in the high-rise building, since there is high probability that the differential pressure formed between the accommodation and the lobby is smaller or larger than the design standard, the installation purpose of the pressurized smoke control system 1 cannot be achieved, and so the improvement for the above has been required.